Always trust your instincts. The first test is to make sure the material feels good to the touch. A quality dress shirt should be woven from 250 two-ply cotton and have split-yoke detailing (the yoke is cut in two and sewn up the middle rather than placed in as one piece). Also, make sure the shirt is single-needle stitched—more yarn is used, but seams are stronger. Last, look at the components of the shirt. Are the sleeves set into the shirt and neatly sewn? Are the placket and cuffs sewn on separately? And pay attention to the buttons: Mother-of-pearl is preferable to plastic.